We use Pfff internally to generate code-graph of large polyglot code-bases (think AOSP). This graph powers the querying engine that finds all tests to be run given a diff. It is incredibly useful. My only gripe is that Pfff isn't being maintained. Pfff can barely support Java 7, let alone Java 8. C/CPP support isn't as extensive as is for PHP. How I wish Pfff was being actively maintained...

I've found Sourcegraph's srclib.org (Go) and Google's kythe.io (Cpp, Go) make some interesting strides in the static analysis field as well.

IMO, treating code as query-able data can open up a lot of possibilities, and OCaml suites the field like a glove.